EXCEED THE SPACE PROVIDED. The paramyxovirus family contains both established major human pathogens, including measles virus and respiratory syncytial virus, and newly emerged human pathogens, the Hendra and Nipah viruses. The fusion (F) proteins from paramyxoviruses promote fusion of viral and cellular membranes, an event that is both an essential step mediating entry of enveloped viruses into the host cell and an excellent model system for investigating the basic molecular events in membrane fusion processes. The long-term objective of this proposed research is to understand the precise mechanism(s) of the paramyxovirus F proteins in promotion of membrane fusion. The central hypothesis of this research proposal is that regions of the paramxyovirus F proteins that are critical for promotion of membrane fusion will be conserved between disparate members of the family, and that analysis of these regions will aid in understandingthe precise mechanisms of the F proteins in promotion of membrane fusion. The experiments in Specific Aim 1 will utilize transient expression systems and site-directed mutagencsis to analyzethe synthesis and processing of the F protein from Hendra virus, a recently discovered human pathogen. The research proposed in Specific Aim 2 will characterize the membrane fusion event promoted by the Hendra virus F protein, using several different membrane fusion assays which allow for examination of various stages of the reaction. Finally, the experiments in Specific Aim 3 will examine the effect of mutations in the SV5 F and Hendra F proteins in regions that show amino acid conservation throughout the paramyxovirusfamily, to determine whether these changes effect folding, protein processing or promotion of membrane fusion. Accomplishing these goals will provide crucial information on the processing and fusion-promotion activity of a paramyxovirus F protein from a newly emerged virus. In addition conserved regions of the F proteins that are important in function will be identified. The results of all of these studies will provide significant new information relevant to understanding specific molecular events involved in membrane fusion processes. PERFORMANCE S1TE(S) (organization, city, state) University of Kentucky. Lexineton. KY KEY PERSONNEL. See instructions Name Rebecca Ellis Dutch Michael Sheehan Willie Craft, Jr. Patrick Segeleon on Page 11. Use continuation pages as needed to provide the required information in the format shown below. Organization Role on Project University of Kentucky Principal Investigator University of Kentucky Graduate Student University of Kentucky Graduate Student University of Kentucky Senior Lab Technician PHS 398 (Rev. 4/98) Page 2 BB Number pages consecutively at the bottom throughout the application. Donal usesuffixes such as 3a, 3b. CC iS^HWrapcal Investigator/Program Director (Last, first, middle): P^i, Rebecca, Ellis Type the name of the principal investigator/program director at the top of each printed page and each continuation page. (For type specifications, see instructions on page 6.) RESEARCH GRANT TABLE OFCONTENTS Page Numbers Face Page 1 Description,